Icap (IAP) shares rose nearly 11% in London's benchmark FTSE 100 index, bringing gains made this week to 14.6%. Over the month, the shares are down 9.2%, including a sharp drop last Friday.

The firm's shares tumbled last week after it cut its earnings forecast, saying slower trading in key markets meant new businesses were taking longer to achieve profitability. See story on Icap profit warning.

However, several brokers have turned more positive on the stock after the fall and it was upgraded on Monday by Credit Suisse to outperform from neutral, citing valuation.

Overall, the U.K. FTSE 100 index (UKX) rose 0.4%, or 20.15 points, to 5,131.99. Other European shares also gained while U.S. stocks slipped in early trading. See Europe Markets.

Ahead of an informal meeting of European leaders on Thursday, representatives of Germany and other European Union members were in discussion on stepping in to support Greece. Read more on rescue speculation.

"While no decision has been taken yet, it seems that Greece will receive support rather earlier than later. The European Union wants to prevent the crisis from spreading to other peripherals," said strategists at Commerzbank.

"We can only speculate on the type of support to be given. However, we still believe that the focus will probably be on guarantees for Greek government bonds," said the strategists. "Support for Greece would massively reduce uncertainty on the markets," they added.

The U.K. has its own debt burden. Sterling dropped 0.6% to $1.5610 against the dollar.

The door remains open to further purchases of government bonds and other assets if deflationary threats reappear, Bank of England Governor Mervyn King said Wednesday.

He added that "enormous" policy stimulus and the pound's depreciation are meeting headwinds created by the banking sector's balance sheet adjustment. Read more on BoE Inflation Report.

Banks advanced in London on Wednesday, with Barclays (BARC)
BCS, -2.09%
shares up 3.2% and Lloyds Banking Group (LLOY)
LYG, -1.57%
up 3.7%.

Fourth-quarter net income rose to 448 million pounds ($702 million), from 393 million pounds a year ago. Revenue climbed to 2.1 billion pounds, from 1.8 billion pounds last year.

Autonomy (AU) shares fell 5.5%. The software firm said that it will raise 500 million pounds via a bond issue and will use the proceeds to pay down debt and for acquisitions.

Part of that process looks to have started already after the firm set out plans on Tuesday to buy MicroLink -- a reseller of Autonomy's software -- for $55 million.

"The market has reacted badly to these announcements and we believe they will not help the market's view of management. Many market participants had been hoping for a clean period of results to allow the true organic growth of Autonomy to be observed," said analysts at Killik & Co.

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